Device for laminating a layered structure consisting of at least two plastic strips in sections

ABSTRACT

The invention relates to a device for laminating a layered structure ( 1 ), consisting of at least two plastic strips in sections, comprising successive panels with designs, for producing plastic cards along a conveyor path. Said device comprises heating and cooling devices ( 8, 9, 10, 11 ) which are positioned one behind the other and consist of individual compression elements, located on a common support ( 14 ), whose temperature can be controlled and which accommodate a whole number of panels and a drive unit which displaces opposing compression belts ( 2, 3 ) which can be driven intermittently in a direction of transport and between which the plastic strips can be displaced in sections through the heating and cooling devices. The aim of the invention is to provide a device which permits the production of plastic cards with a higher laminate quality. To this end, the compression elements are mounted so that they can be displaced in the direction of the conveyor path against a restoring force which acts upon their initial position.

BACKGROUND OF THE INVENTION

The present application is a 371 National Stage of co-pendingapplication PCT/DE00/03213 having an international filing date of Sep.15, 2000, and a priority date of Sep. 17, 1999, entitled “Device forLaminating A Layered Structure Consisting of At Least Two Plastic Stripsin Sections”.

1. Field of the Invention

The invention relates to a device according to the precharacterizingclause of claim 1 for laminating in sections a layered structureconsisting of at least two plastic strips, comprising successivelyformed panels with designs, for producing plastic cards along aconveying path, comprising successively arranged heating and coolingdevices, which are formed by individual temperature-controllablepressing elements which accommodate an integer number of panels and arearranged on a common support, and a drive unit, which displaces mutuallyfacing pressing bands which can be driven intermittently in a conveyingdirection and between which the plastic strips can be moved in sectionsthrough the heating and cooling devices.

2. Related Art

EP-B-0 134 820 describes a device which, for a continuous production ofplastic cards, in particular credit cards, check cards, access cardsetc., allows a synchronous feed of plastic strips into a laminatinginstallation for the forming of a laminate. The plastic strips consistof individual panels which are separate from one another and arearranged one behind the other in one or more rows. The laminatinginstallation comprises heating and cooling devices made up oftemperature-controllable pressing elements which are arranged on alongitudinal support and the dimensions of which are chosen for thetreatment of an integer number of panels at a time and allow baking insections of the plastic strips forming a layered structure, withsubsequent cooling. By arrangement between mutually facing endlesspressing bands which can be driven in a cyclical manner, the at leasttwo plastic strips are moved into treatment zones for the pressingelements, in which the heating-pressure effect and the cooling-pressureeffect is transferred to the plastic strips. The plastic strips arelaminated in sections as a result. For this purpose, the pressingelements respectively comprise a fixed lower pressing bar and a movableupper pressing bar, between which the pressing bands come into contactduring the heating/cooling-pressure treatment.

However, it has been found to be disadvantageous that, in rapidtreatment, the temperature-controlled web with high temperatures of theplastic strips to be laminated lead to high local instances of expansionand shrinkage of the pressing bands and possibly of the plastic strips,to be precise in particular in the edge region of the pressing zones,where discontinuous temperature and pressure conditions prevail. Thisleads to high loading with compressive and tensile forces and possiblyto damage of the pressing bands, so that they are subject to a highdegree of wear. If, to increase the rate of production, the shortestdwell times are used for heat treatment, but, to compensate for this,high temperatures, this disadvantageous wear increases. Furthermore,laminating defects occur at the panels and lead to an undesiredrejection rate, since there is a high requirement for the surface ofsuch plastic cards to be defect-free.

DE-C-42 05 746 describes a device for adhesively bonding sheet-likeworkpieces, in particular for concealing plastic parts in sheet form, inwhich a depositing station, a heating station, a pressing station and acooling station, arranged outside the pressing station, are successivelyarranged. The workpieces to be adhesively bonded are passed individuallyin succession by means of a lower transporting belt first through theheating station and subsequently through a pair of pressing rolls of thepressing station. The pressing station, defined by the pair of pressingrolls, serves at the same time as a deflecting roller for transportingbelts and is not movable with respect to the conveying path. The heatingstation comprises two heating plate units, which respectively has a linkchain comprising a plurality of chain links, on which there are mountedtransverse supports, which run transversely with respect to theconveying direction and have heating elements. The links of the linkchain are respectively connected via intermediate links on both sides toa drive cylinder, via a driving shaft, by the actuation of whichcylinder the two link chains of the heating plate units can beconfigured such that they are parallel to each other, bulging outsubstantially in the same direction or else converging in a wedge-shapedmanner. Although the link chains of the heating plate unit areadjustable, this adjustment does not permit a movable arrangement of theheating elements, or even of the pressing station, nor the movement inthe direction of the conveying path, on account of the static adequatelydetermined fixed position of the drive cylinders. A cooling press is notprovided. The position of the chain links is static.

It is the object of the invention to provide a device which allows theproduction of plastic cards with high laminating quality at high ratesof production.

SUMMARY OF THE INVENTION

This object is achieved according to the invention by burning a devicefor laminating the layered structure consisting of at least two plasticstrips in sections including successively formed panels with designs forproducing plastic cards along a conveying path. The device includessuccessively arranged heating devices and cooling devices, which areformed by individual temperature-controllable pressing elements, whereineach pressing element accommodates an integer number of panels, andwherein the pressing elements are arranged on a common support. A driveunit is provided which displaces mutually facing pressing bands, whereinthe pressing bands can be driven intermittently in a conveyingdirection, and wherein plastic strips can be moved in sections betweenthe pressing bands through the heating and cooling devices. The pressingelements are arranged such that they can be moved in the direction ofthe conveying path against a restoring force, which acts toward theirinitial position.

This provides a device for laminating in sections a layered structureconsisting of at least two plastic strips, comprising successivelyformed panels with designs, for producing plastic cards along aconveying path, which device transfers the temperature-induced localchanges in length of the pressing bands to the positioning of thepressing elements, by the latter being able to follow axialdisplacements and thereby permit a compensation to take place. Undesiredloads of the pressing bands and of the plastic strips in thelongitudinal direction are avoided as a result. Consequently, operationeven with short cycle times and resultant high temperatures is possiblewithout any defects occurring.

It is advantageous in this case that, by incorporating in the design adissipation of the axial distortion forces occurring, the deviceresponds directly, so that it is possible to dispense with complexcontrollers for this purpose.

The device according to the invention advantageously decouples adjacentpressing elements, so that the pressing elements can have a slightchange in their distance from each other in the conveying direction.This makes it possible for the cyclically or intermittently drivenpressing bands and the plastic strips lying in contact with them, whichare exposed to locally different temperatures on account of thedifferently temperature-controlled pressing elements, to be positionedprecisely in the pressing elements. The stresses otherwise acting on thepressing bands or plastic strips are greatly reduced as a result.

In an advantageous configuration of the invention it is provided that,during a stop in production, a raising device, raising the upperpressing bar, can be actuated for further opening of the pressingelements, the opening movement of the upper pressing bar being small innormal operation, to permit the advancement of the pressing bands. Alsoprovided is a lifting device, which, in the event of a stop inproduction, raises the pressing bands simultaneously, in order tointerrupt a contact bridge between the pressing bands and the lowerpressing bar during the opening of the pressing element. As thishappens, the pressing bands are displaced into an approximatelycentrally arranged position between the lower and upper pressing bars.Undesired overheating of the pressing bands is avoided as a result,since the pressing bands then only serve as heat-transferring meansduring the heating-pressure treatment itself. This significantlyincreases the service lives of the pressing bands. In particular in thecase of a fault or maintenance, overheating of the plastic strips, whichwould otherwise result in extensive setting-up work, is effectivelyprevented.

The pressing bands are expediently placed in each case over a running-indrum, arranged outside the pressing elements, and a running-out drum. Atleast one of the drums has a peripheral portion with precision spikes,which is in drive connection with a transporting perforation provided inan edge zone of an assigned pressing band. The spiked portion permitsexact registration and slip-free guidance of the pressing band. Theheight of the spikes is about 0.5 mm.

The spikes have an upwardly rounded form. Each of the drums ispreferably provided with a spiked portion, the running-in drums and therunning-out drums being offset in relation to one another to avoid thespikes hitting one another. The offset of the drums in the running-inregion and in the running-out region is preferably identical and in thesame direction, so that an identical band can be used for both pressingbands.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and features of the invention emerge from thefollowing description and from the dependent claims.

The invention is explained in more detail below with reference to theattached drawings on the basis of preferred exemplary embodiments.

FIG. 1 schematically shows a side view of a first exemplary embodimentof a device according to the invention for laminating in sections, as asubstation of a complete installation for the production of plasticcards.

FIG. 2 schematically shows a side view of the device from FIG. 1, withraised upper pressing bar.

FIG. 3 schematically shows a partial side view of a second exemplaryembodiment of a device according to the invention for laminating insections, as a substation of a complete installation for the productionof plastic cards.

DETAILED DESCRIPTION

FIG. 1 shows a device for laminating in sections a layered structure 1consisting of at least two plastic strips, comprising successivelyformed panels with designs, as a substation of an installation forproducing plastic cards along a conveying path. The plastic stripsforming the layered structure 1 are synchronously fed in, the variousplastic strips to be laminated to form a laminate having previously runthrough different processing stations, in which the panels may have beenprovided with synchronization holes and with printed images, informationcarriers, punched perforations, etc., to prepare the plastic cards to beproduced for the respectively intended purpose. The average thickness ofthe plastic strips to be processed preferably lies around 0.1 to 3 mm,depending on how many plastic strips form a layered structure 1. Thetotal thickness of the finished plastic cards usually lies in the rangearound 0.8 mm. Four plastic strips are preferably brought together toform a layered structure 1, to be precise a transparent film strip onthe upper side and underside and two middle printed insert strips.

Once the at least two plastic strips have been brought together, theyform the layered structure 1, which runs into a nip between two pressingbands 2, 3. The pressing bands 2, 3 are formed by two uninterrupted,mutually facing endless bands, which are respectively placed over arunning-in drum 4, 5 and a running-out drum 6, 7. At least one of thebands, for example the lower band, is driven in steps and, during itscirculating movement, takes with it the layered structure 1 and theother band, if the latter is not driven synchronously with it. In theirouter edges, the pressing bands 2, 3 have a continuous transportingperforation, which respectively meshes with a spiked portion of the fourdrums 4, 5, 6, 7 and establishes an unequivocal, relatively unchangeableposition. In order that the pressing bands 2, 3 operate as slip-freecarriers for the layered structure 1, devices for in-register transportin the conveying direction are provided. Devices of this type are in thepresent case pins which are provided on at least one pressing band andengage in aligned register holes of the layered structure 1 and of theother pressing band. Alternatively, adhesively attaching devices canalso be used. This establishes the position of the layered structure 1between the pressing bands 2, 3. Driving of the pressing band providedwith the pins and the transport perforation leads to precise positionsof the layered structure 1 in heating devices and cooling devicesdescribed below. As a result, the surface of the pressing bands 2, 3facing the layered structure embosses the surface of the layeredstructure.

Successively arranged along the pressing bands 2, 3 are heating devices8, 9 and cooling devices 10, 11, which are formed by individualtemperature-controllable pressing elements. The number of heatingdevices 8, 9 and cooling devices 10, 11 arranged next to one another isselectable. The heating devices 8, 9 and the cooling devices 10, 11 arerespectively arranged such that they are spaced apart from one another,their spacing following the spacing of the panels of the layeredstructure 1, in order that the heating and cooling devices 8, 9, 10, 11respectively act on an integer number of panels.

The heating devices 8, 9 and cooling devices 10, 11 are designed aspressing elements, with in each case an upper pressing bar 12 and alower pressing bar 13. Between the upper pressing bar 12 and the lowerpressing bar 13 of a number of pressing elements, the layered structure1 runs through, guided between the two pressing bands 2, 3, in aconveying direction which runs from right to left in FIGS. 1 and 2. Thepressing elements designed as heating devices 8, 9 are heatableelectrically or by means of a temperature-controllable fluid, while thepressing elements designed as cooling devices 10, 11 are preferablywater-cooled. It is alternatively possible to provide each of theheating devices 8, 9 and cooling devices 10, 11 with a dedicated upperand lower die.

FIG. 1 shows the respective pair of pressing bars 12, 13 in a closedposition of the pressing elements for a temperature-controlled pressuretreatment of the layered structure 1, at least the upper pressing bar 12being movable in the manner of a die, in order to exert a compressiveforce on the lower pressing bar 13. After completion of atemperature-controlled pressure treatment, the pressing elements areopened, by slightly raising the respectively upper pressing bar 12, andthe pressing bands 2, 3 with the layered structure 1 treated in sectionsare advanced in the conveying direction, for example the section of thelayered structure 1 treated in the heating devices 8, 9 is moved intothe region of the cooling devices 10, 11.

In normal operation, the upper pressing bar is raised by a small amount,the pressing bands are displaced, and the upper pressing bar is loweredagain, in order to transfer the temperature. In the event of a stop inproduction, the wide opening of the upper pressing bar 12 is detected bya control device 13, in particular initiated and determined by thelatter, which actuates a lifting device 31, 32, in order to raise thepressing bands 2, 3, which come into contact between the pressing bars12, 13, from the lower pressing bars 13 when the pressing elements openwide. The lifting device 31, 32 is formed here by lifters which arearranged on the inlet and outlet sides of the heating and coolingdevices 8, 9, 10, 11 and can be moved upward as compared with adisengaged position with respect to the pressing bands 2, 3, with avertical component, as represented in FIG. 2. As a result, the pressingbands 2, 3, extending between the pressing bars 12, 13 of the pressingelements, are brought definitely out of contact with the lower pressingbars 13, and preferably into a raised midway position between the twopressing bars, along the treatment zone defined by the heating andcooling devices, when the upper pressing bar 12 opens wide or has openedwide. The distance of the pressing bands 2, 3 from the lower and/or theupper pressing bar 13, 12 is preferably between 1 cm and 35 cm.

As an alternative to the lifters represented in FIGS. 1 and 2, otherlifting devices, for example a compressed-air actuator, may be provided.

The individual pressing elements are individually adjustable with regardto their temperature and the pressure exerted by them, the layeredstructure 1 remaining between the presses for the heating-up andcooling-down process. The temperature and pressure are chosen such thatthe baked and cooled layered structure 1 forms a stable laminate. For astepped advancement of the layered structure 1, the presses are in eachcase opened slightly. Then, the section of the layered structure 1 whichhas been treated by the heating devices 8, 9 is moved with a cyclicaladvancement into the treatment region of the cooling devices 10, 11, sothat the layered structure 1 preferably runs in sections through aheating-up process and a cooling-down process. The duration of theheating-up and cooling-down processes determines the cycle times.

The heating devices 8, 9 and cooling devices 10, 11 are arranged on acommon support 14, which sets up the individual pressing elements of theheating devices 8, 9 and of the cooling devices 10, 11 such that theycan be displaced axially against a restoring force. The lower pressingbars 13 are arranged on the support 14.

According to FIG. 1, the support 14 is designed as a straightlongitudinal support, which is supported at both ends by bearings 15, 16and has predetermined bending points 17, 18, 19 between respective pairsof successive pressing elements of the heating and cooling devices 8, 9,10, 11. The predetermined bending points 17, 18, 19, which allow localsagging or upward bending of the support 14, are formed by slits 21, 22,23, which extend in the direction of a supporting surface 20 of thelongitudinal support and beneath which the support 14 rests resilientlyon bearings 24, 25, 26. The slits 21, 22, 23 cut partly through thesupport 14, transversely with respect to the longitudinal axis, the slitlength in the direction of the supporting surface 20 determining thedegree of bending. What is important here is that the predeterminedbending points 17, 18, 19 respectively lie between the individualheating and cooling devices 8, 9, 10, 11, transversely with respect tothe longitudinal axis, to be precise as centrally as possible betweenthem, to be able to follow instances of expansion and shrinkage of thepressing bands 2, 3, whereby the latter are relieved.

The structural design described above allows a shrinkage or expansion ofthe pressing bands 2, 3, and possibly of the layered structure 1, thatis induced by a temperature change and occurs in the region between twoheating and cooling devices 8, 9, 10, 11, to bring about a local upwardbending or sagging of the support 14 in this assigned region, wherebythe distance between the pairs of heating and cooling devices 8, 9, 10,11 is increased or reduced. This load builds up a restoring force, whichfollows from the residual rigidity of the support 14 left by the slits21, 22, 23 and from the resilient bearings 24, 25, 26. Thedesign-imparted compensation for a temporary upward bending or saggingcaused by the pressing bands 2, 3 can be carried out individually, i.e.the various predetermined bending points can be subjected to differentloading.

FIG. 3 shows a second exemplary embodiment of a device for laminating insections a layered structure 1 consisting of at least two plasticstrips, comprising successively formed panels with designs, forproducing plastic cards along a conveying path, which differs from thefirst exemplary embodiment described above in that, for the axialdisplaceability of the individual pressing elements in relation to oneanother, against a restoring force, the successive pressing elements ofthe heating and cooling devices 8, 9, 10, 11 are arranged in relation toone another such that they can be displaced axially with respect to thelongitudinal support 14 by means of roller mountings 40, 41. In thiscase, the pressing elements are supported in the conveying directionrespectively between two stops 42, 43, limiting the axialdisplaceability, on said stops by means of springs 44, 45.

The structural design described above allows a shrinkage or expansion ofthe pressing bands 2, 3 arriving in the heating devices 8, 9 and coolingdevices 10, 11, that is induced by a temperature change and occurs inthe region between two heating and cooling devices 8, 9, 10, 11, tobring about a local axial displacement of a pressing element of aheating or cooling device. The adjustable spring forces re-establish thestate of equilibrium, in which the respective pressing element assumes abasic position.

What is claimed is:
 1. A device for laminating in sections a layeredstructure consisting of at least two plastic strips comprisingsuccessively formed panels with designs for producing plastic cardsalong a conveying path, comprising successively arranged heating devicesand cooling devices, which are formed by individualtemperature-controllable pressing elements, wherein each pressingelement accommodates an integer number of panels, and wherein thepressing elements are arranged on a common support, and a drive unit,which displaces mutually facing pressing bands, wherein the pressingbands can be driven intermittently in a conveying direction, whereinplastic strips can be moved in sections between the pressing bandsthrough the heating and cooling devices, wherein the pressing elementsare arranged such that they can be moved in the direction of theconveying path against a restoring force which acts toward their initialposition.
 2. The device as claimed in claim 1 wherein the successivepressing elements are arranged on a straight longitudinal support,wherein the support is supported at both ends and has predeterminedbending points between respective pairs of successive pressing elements.3. The device as claimed in claim 2 wherein the predetermined bendingpoints are formed by slits which extend in the direction of a supportingsurface of the longitudinal support and beneath which the longitudinalsupport resiliently rests such that sagging or upward bending of thesupport is achieved.
 4. The device as claimed in claim 3 wherein theslits go through the longitudinal support transversely with respect tothe conveying path.
 5. The device as claimed in claim 1 wherein thesuccessive pressing elements are arranged in relation to one anothersuch that they can be displaced axially with respect to the longitudinalsupport by means of roller mountings.
 6. The device as claimed in claim5 wherein the pressing elements are arranged in the conveying directionrespectively between two springs supported on stops limiting the axialdisplaceability.
 7. The device as claimed in claim 1 wherein one of thepressing bands comprises positioning pins which engage in registeropenings of the plastic strips and of the other of the pressing bandsfor a positionally exact guidance of the plastic strips in a laminarstructure through the pressing elements.
 8. The device as claimed inclaim 1 wherein temperature, pressure and processing time of theheatable pressing elements are adjustable by means of a control unit. 9.The device as claimed in claim 8 wherein a processing time of thecoolable pressing elements is adjustable in dependence on the processingtime of the heatable pressing elements by means of the control unit. 10.The device as claimed claim 1 wherein a fixed lower pressing bar and amovable upper pressing bar are provided, and wherein a lifting deviceraising the pressing bands with respect to the lower pressing bar isprovided that is capable to be actuated by a control device detecting anopening of the upper pressing bar.
 11. The device as claimed in claim 10wherein the lifting device comprises movable lifters which are arrangedon an inlet side and on an outlet side of the heating and coolingdevices.
 12. The device as claimed in claim 1 wherein the pressing bandsare respectively placed over a running-in drum and a running-out drum,wherein the running-in drum and the running-out drum are arrangedoutside the pressing elements, and wherein at least one of the drums hasa peripheral portion with precision spikes which is in drive connectionwith a transporting perforation provided in an edge zone of an assignedpressing band.
 13. The device as claimed in claim 12 wherein the drumsof at least one of the pairs of running-in drum and running-out drum arearranged offset in relation to one another in the conveying directionand have a peripheral portion with precision spikes.
 14. A device forlaminating in sections a layered structure consisting of at least twoplastic strips, comprising successively formed panels with designs, forproducing plastic cards along a conveying path, comprising successivelyarranged heating devices and cooling devices, which are formed byindividual temperature-controllable pressing elements, wherein eachpressing element accommodates an integer number of panels, and whereinthe pressing elements are arranged on a common support, wherein thesupport comprises a fixed lower pressing bar and a movable upperpressing bar, and mutually facing pressing bands which can be drivenintermittently in a conveying direction, by means of which the plasticstrips arranged between the pressing bands can be moved in sectionsthrough the heating and cooling devices, and a lifting device forraising the pressing bands with respect to the lower pressing bar,wherein the lifting device can be actuated by a control device detectingan opening of the upper pressing bar.
 15. The device as claimed in claim14 wherein the lifting device comprises movable lifters which arearranged on an inlet side and on an outlet side of the heating andcooling devices.
 16. The device as claimed in claim 14 wherein thepressing bands are respectively placed over a running-in drum and arunning-out drum, wherein the running-in drum and the running-out drumare arranged outside the pressing elements, and wherein at least one ofthe drums has a peripheral portion with precision spikes which is indrive connection with a transporting perforation provided in an edgezone of an assigned pressing band.
 17. The device as claimed in claim 14wherein one of the pressing bands comprises positioning pins whichengage in register openings of the plastic strips and of the other ofthe pressing bands for a positionally exact guidance of the plasticstrips in a laminar structure through the pressing elements.
 18. Thedevice as claimed in claim 14 wherein the pressing elements are arrangedsuch that they can be moved in the direction of the conveying pathagainst a restoring force which acts toward their initial position. 19.The device as claimed in claim 18 wherein the successive pressingelements are arranged on a straight longitudinal support, wherein thesupport is supported at both ends and has predetermined bending pointsbetween respective pairs of successive pressing elements, and whereinthe predetermined bending points are formed by slits which extend in thedirection of a supporting surface of the longitudinal support andbeneath which the longitudinal support resiliently rests such thatsagging or upward bending of the support is achieved.